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Biomedical subjects

C Zwicker

Publications and source records attributed to C Zwicker.

At least 19 recordsLinked to original sources
PubMed1998

[Radiotherapy of humero-scapular periarthritis using ultra-hard photons. Evaluation by MRI findings].

PURPOSE: Evaluation of MRI in radiotherapy of humeroscapular periarthritis. PATIENTS AND METHODS: Seventy-seven patients with humeroscapular periarthritis prospectively underwent MRI before radiotherapy. RESULTS: Six months after radiotherapy, 34% of the patients had achieved complete pain relief, 35% major pain relief. Twenty percent had only slight improvement and 12% no improvement. Positive correlation of radiotherapy outcome and MRI findings could be shown for acute tendinitis, erosions, and complete and incomplete ruptures of the supraspinatus tendon. CONCLUSIONS: Radiotherapy is highly effective in the treatment of humeroscapular periarthritis. The indication can be improved using MRI.

Aged↗
PubMed1998

Septum orbitale: high-resolution MR in orbital anatomy.

PURPOSE: The purpose of this study was to ascertain whether MR imaging, with the use of a surface coil, can accurately show small intraorbital structures; in particular, the septum orbitale. METHODS: Examinations of 26 patients who underwent unilateral orbital high-resolution MR imaging for different indications were evaluated to differentiate the septum orbitale from related structures, such as the aponeurosis of the levator palpebrae, the superior tarsal (Müller's) muscle, and the superior orbital (Whitnall's) ligament. RESULTS: A subtle differentiation of the septum orbitale was obtained in 23 patients (88%) and of the levator aponeurosis and Müller's muscle in 24 patients (92%). The orbicularis oculi muscle and the submuscular fibroadipose tissue were reliably identified in all patients. CONCLUSIONS: High-resolution MR imaging is suitable for differentiating small intraorbital structures. Nevertheless, an exact depiction of the septum orbitale remains very much dependent on the cooperation of the patient. The site of orbital disease can be determined precisely and in a noninvasive manner in relation to the septum orbitale.

Aged↗
PubMed1998

[Multi-project angiography in the imaging of cerebral aneurysm].

In spite of procedures such as CT angiography, MR angiography, and rotation angiography, panangiography is still indispensable in therapeutic planning for cerebral aneurysms. It is the only method that provides exact details about the size, anatomic localization, and multiplicity of aneurysms as well as relation to surrounding vessels, the presence of an aneurysmal neck, and for the evaluation of the collateral circulation required to answer the question if endovascular therapy is possible. In addition, panangiography still exhibits the highest selectivity in the detection of cerebral aneurysms.

Angiography↗
PubMed1997

Computed tomography with iodine-free contrast media.

The purpose of this work was to evaluate the enhancement of different concentrations of gadolinium (Gd), ytterbium (Yb) and iodine in vitro and in vivo. Comparisons were made of the enhancement (HU) of Gd, Yb and iodine in concentrations ranging from 0.1 to 30 mg/ml. In vivo dynamic CT studies were performed in ten dogs with 0.5 M Gd, Yb and iodine. Time-density curves were achieved in aorta and liver. The in vitro studies confirmed a decrease in the enhancement in this order: Gd (120 kV) > Gd (137 kV) > Yb (120 kV) > Yb (137 kV) > iodine (120 kV) > iodine (137 kV). The specific enhancement of Gd was 40.8 (120 kV), of Yb 34.2 and of iodine 29.6 HU. The enhancement of the liver decreases from 21 HU (Gd) to 19 HU (Yb) and 12 HU (iodine). Gd and Yb achieved a higher aortal enhancement than iodine (190 vs 157 HU) All contrast media were well tolerated. Equimolar concentrations of Gd and Yb show a higher in vitro contrast and enhancement than iodine.

Animals↗
PubMed1997

[Computerized tomography differentiation of hepatocellular carcinoma and cholangiocellular tumors].

20 patients with hepatocellular carcinomas (HCC) and 18 patients with tumours of the biliary passages and gallbladder (CAC)) were examined via angio-CT without table increment and via spiral CT. Evaluation of the time-density curve of angio-CT showed more rapid and greater enhancement in case of HCC, whereas CAC were characterised by slower and lesser contrast medium uptake than the surrounding hepatic tissue. Superior differential diagnostic information was obtained via angio-CT, whereas spiral CT yields the best information on extent and number of hepatic tumours.

Aged↗
PubMed1994

Value of magnetic resonance imaging in staging carcinomas of the oral cavity and oropharynx.

The value of magnetic resonance imaging (MRI) in preoperative tumor (T) staging was assessed prospectively in 46 patients with malignant carcinomas of the oropharynx and oral cavity. In each case, the MRI findings were compared with the preoperative clinical and postoperative histopathologic findings. MRI showed an accuracy of 89% in identifying the T stage, as compared with the histopathologic result. The accuracy of the clinical examination was 78%. Compared with the clinical examination, MRI is particularly suited for differentiating T3/T4 and the larger T2 tumors. MRI tends to overinterpret the T stage when the neighboring tissues are inflamed or edematous, as it allows no demarcation between inflamed or edematous tissue and tumor. Moreover, normal oropharyngeal mucous membrane and intrinsic tongue muscle both absorb contrast medium. In the clinical examination, the T stage is often underestimated, as the depth of infiltration and bone involvement cannot always be determined with certainty. The ability of MRI to give an axial, coronal, and sagittal image allows an exact preoperative view of tumor spread and assessment of infiltration into adjacent structures.

Adult↗
PubMed1993

[Lymph node metastases of the neck in unknown primary tumor: is there a differential imaging diagnosis?].

In 32 patients suffering from cervical lymph node metastases with an unknown primary tumour the pretherapeutic findings via sonography, CT and MR were compared and the post-therapy findings of tumour aftercare assessed. After an average follow-up period of 38 months the group of branchiogenic cervical cysts had no recurrence. In the group of 18 patients with more than one cervical lymph node metastasis without primary tumour, either the primary tumour or further lymph node metastases became manifest in 11 patients after an average follow-up period of 36 months. Imaging of the number of lymph node metastases and differentiation between malignant degenerated branchiogenic cysts and lymph node metastases without primary tumour is important for prognosis. A combination of findings from sonography, CT and MR enables performance of such differential diagnosis due to morphological aspects and aspects that are conditioned by the contrast medium.

Adult↗
PubMed1993

[CT contrast administration of iodine, gadolinium and ytterbium. In-vitro studies and animal experiments].

The absorption of the elements iodine, gadolinium and ytterbium in various dilutions was studied in relation to CT. Regression analysis and specific CT density measurements showed that absorption decreases from gadolinium to ytterbium and iodine. These results were confirmed by experiments using ten dogs. Boli of 0.5 molar gadolinium used for angio-CT without table movement showed the largest increase in density in the aorta and liver with an average of 190HU and 21HU respectively compared with iodine which gave 157HU and 12HU respectively. The animal experimental studies suggest that gadolinium and ytterbium are suitable contrast media for dynamic CT investigations.

Absorption↗
PubMed1993

[Color duplex sonography of liver transplantation. The vascular status].

The present study deals with the value of CDS in liver transplantation. Between September 1988 and October 1991 CDS of hepatic vessels was carried out in 194 liver transplants. Flow direction and flow velocity in the portal vein could be demonstrated in 97%. Measurement of flow velocity indicates the extent of portal hypertension; this can be confirmed by determining flow direction in the splenic and superior mesenteric veins. In 47 of 179 patients venous collaterals were demonstrated and in 15 of 179 patients there was retrograde flow in the splenic vein. In 95% of patients CDS indicated flow direction in the hepatic artery and in 93% in the hepatic veins. Thrombosis of liver vessels (portal and hepatic veins) was demonstrated in 11 out of 13 patients by means of CDS.

Budd-Chiari Syndrome↗
PubMed1993

[Feasibility of the differential diagnostic imaging of neck lymphomas].

In 51 patients with cervical swellings, pretherapeutic examinations by ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) were carried out for the confirmation of exclusion of cervical lymph node metastases. By use of the M/Q ratio and morphological criteria, it is possible with ultrasound to differentiate between relatively enlarged lymph modes and lymph node metastasis with a certainly of > 90%. This was only possible in CT after administration of contrast media and the success rate was lower (72%). Both by use of the M/Q ratio and contrast medium administration, MRI is able to distinguish between lymph node metastases and reactively altered lymph nodes. Differentiation between Hodgkin/non-Hodgkin lymphomas of the neck and reactively enlarged lymph nodes is also possible with the aid of the M/Q ratio. In such cases, sonography and MRI are superior to CT. A certain differentiation between lymph node metastases and Hodgkin/non-Hodgkin lymphomas is only possible in some cases. However, there are indicative criteria for differential diagnosis. A delineation between specific lymph node inflammations and glomus carotid tumors is also possible because of the differing take-up of contrast medium in CT and MRI and via doppler sonographic criteria.

Diagnosis, Differential↗
PubMed1993

[Diffuse demineralization of the lumbar spine. Magnetic resonance tomography studies of osteoporosis and plasmacytoma].

On plain radiographs, diffuse infiltration of the spine in multiple myeloma may present as diffuse demineralization. Differentiation from osteoporotic changes is then difficult. 15 patients with multiple myeloma and 15 patients with osteoporosis were prospectively examined by MRI using plain and contrast enhanced gradient echo techniques. Examinations were evaluated for lesions and diagnosis was made by two independent observers. Contrast enhancement was visible in lesions detected in myeloma patients and in compression fractures. Fractures could be differentiated from malignant lesions by the fact that there was no multiplicity of enhancing lesions. Contrast enhanced opposed phase gradient echo sequences seem suited for the detection of vertebral involvement in myeloma.

Adult↗